I. Field of the Invention
The present invention relates generally to train positioning systems, particularly to systems for indexing a coupled string or trip of railcars through a work station, to position one or more cars with precision for loading, unloading, washing (etc.) operations. More specifically, the present invention is directed to a system of the class which includes a single self-propelled carriage that operates along a guideway alongside and parallel to a railroad track using an on-board drive that moves the carriage along a single drive chain mounted along the guideway. The carriage uses a single car-engaging device to engage hook loops or hook holes to move the cars along through the work station. The car-engaging device is a horizontally extending cantilevered spike or pin designed to telescope from one side of a car to engage the hook opening. A telescoping gate-opening tool may also be mounted on the carriage for operating gates in bottom discharge cars.
II. Related Art
Uni-Trains, many containing 100 or more cars of identical or a variety of sizes and types, have long been acknowledged as desirable and efficient carriers of bulk raw materials such as coal, iron ore, limestone, various finely divided dry bulk agricultural products including grains, etc., and liquid or dry chemicals. These cars are typically filled from above and may be emptied using a rotary car dumper in the case of coal or iron ore. Liquid bulk cargo is typically unloaded by connecting outlets to large hoses with associated pumping equipment and opening bottom drain valves.
Cars shipping bulk agricultural products are bottom emptied into stationary pits. These cars are provided with a number of spaced bottom discharging hopper bins accessing the main storage volume of the car. These hoppers are closed by horizontal slide gates. When the hoppers are precisely positioned over fixed recessed receiving facilities beneath the railroad track, the gates are opened and the cargo discharged.
In the bottom discharge operation, a connected train engine roughly positions one end of a string of cars to be unloaded close to the unloading facility. However, train engines are not well suited for indexing or precisely positioning individual cars or even sets of cars along the track. Because of this, train positioning devices known as railroad car indexers or movers have been built and operated at fixed stations along the tracks to more precisely position cars for loading or unloading operations.
Railroad car indexers of the class typically include at least one car engaging and propelling member or “dog” for engaging a car in a string or trip of cars and moving the string a given distance along the railroad track. The car-engaging members often situated and operated along an auxiliary indexer track or guideway juxtaposed in parallel relation to the railroad track. Fluid operated actuators such as hydraulic cylinders or chains and sprockets driven by hydraulic or electric motors supply the force for moving railcars. U.S. Pat. No. 4,006,691, issued to Kacir et al, and U.S. Pat. No. 4,354,792, issued to Cornish, show train positioners that approach the train from alongside the track and including an engaging member arm which engages a car coupler from above.
It is known to provide a train positioning system having one or more carriages which include a pair of horizontally pivoting dogs mounted in opposed spaced relation and adapted to operate on a bogey frame such that a first dog engages and pushes on a bogey frame in a first direction and a second opposed dog engaged to push on the bogey frame in the opposite direction. Such a system is illustrated and described in U.S. Pat. No. 6,267,059 to Brandt, a co-inventor in the present application.
Dog-carrying, train-positioning carriages have been proposed using reversing chain drives which include an over/under or vertical sprocket drive system in which the gears and chain are at least partially enclosed to reduce exposure of the mechanism to the elements and the buildup of foreign materials. A system such as this is illustrated and described in U.S. Pat. No. 6,553,916 B2. A further patent, U.S. Pat. No. 6,837,168, discloses a train positioning system that includes a dog carriage having a drive motor mounted on the dog carriage which operates to propel the dog carriage back and forth along a single tension chain in a carriage guideway provided alongside the track. The carriage is supplied with electric power and hydraulic fluid from an attached flexible power track system.
Railroad cars having bottom discharge hopper-type bodies include spaced aligned hoppers which are closed by horizontally disposed gates that are displaced laterally to open and close the bottom of each hopper by drive systems that typically include a rack and pinion mechanism operated by rotating an associated operating rod using an attached capstan. This requires a separate operation utilizing a powered gate operator in which a key or gripper device is used to attach to and rotate each of the capstans. This function has long involved the provision of a separately supplied cantilevered gate operator device utilizing a telescoping chuck to engage a capstan of a railroad car gate. The gate operators are typically separately mounted to operate along their own gate operator platform spaced from, but associated with, a railcar indexing system.
While many of these prior systems have met with success, a need has also existed to simplify cantilever car-engaging systems and to optionally incorporate a gate operating device on the same carriage which carries the car-engaging member. Accordingly, the present invention provides a single telescoping body pin or spike-type car-engaging assembly mounted on a car-moving carriage which engage railcars using the hook loops or holes and also may incorporate a gate-operating assembly mounted on the same carriage. The carriage incorporates on-board drive and hydraulic systems and operates along a guideway using a single strand of drive chain.